French patent 2 647 163 discloses a fixing member comprising a pull rod having an expandable plug mounted thereon and surrounded by a split ring whose length is shorter than the length of the plug, the expandable plug bearing against an endpiece associated with one end of the pull rod.
A bush is threaded onto the other end of the pull rod and bears against the expandable plug via a thrust washer. Finally, a nut is screwed onto the pull rod and enables the endpiece and the bush to be moved towards each other, thereby shortening the plug axially and thus expanding it radially together with the split ring that surrounds it. The inside surface of the split ring has a helical groove.
In that configuration, the axial shortening of the expandable plug is limited to the thrust of the endpiece and of the thrust washer against the opposite faces of the split ring, thereby putting a limit on radial expansion. In addition, at high pressures, there exists problems of the plug creeping and escaping between the endpiece and the circular wall of the hole in which the member is inserted, and also between the thrust washer and said wall, thus making subsequent disassembly and reuse difficult, because of failure of the split ring to shrink radially. It is possible to pull the member out of the hole but only at the risk of damaging the surface thereof, and that is not acceptable when the hole is a tube in a tube plate.